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Air Quality Basics  

1. What is air pollution?

Air pollution is the change in the natural composition of the air we breathe, beyond some defined limits. This change is induced by releasing harmful substances into the atmosphere and it causes damage to our health and environment. Natural sources of air pollution include sea spray, volcanic activity, forest fire, and dust storms. Anthropogenic sources include motor vehicles, industrial production processes, and power generation.

2. What are the main air pollutants and what are their health effects?

The main pollutants that can affect human health are often known as “criteria” pollutants and these include:
 
(a)

Particulate matter

Particulate matter is the general term used to describe a mixture of solid and liquid particles in air including dust, soot, smoke, and dirt. PM10 is particulate matter less than 10 microns in aerodynamic diameter and is often called the coarse fraction. PM2.5 is particulate matter less than 2.5 microns (about 0.0001 inch) in aerodynamic diameter and is often called the fine fraction.

PM10 and PM2.5 particles are small enough to penetrate into and accumulate in the respiratory system. Exposure can cause respiratory morbidity, impaired lung function and irritation. It is also carcinogenic. This pollution is sometimes referred to as “black carbon pollution”.

(b)

Nitrogen dioxide

Nitrogen dioxide (NO2) is a noxious gas, highly reactive and it is formed when fuel is burned at high temperature. The main sources are motor vehicles, power plants and industrial boilers. Nitrogen dioxide can cause respiratory problems. It can also take part in the chemical reactions in the atmosphere to form corrosive nitric acid and can also react with sunlight to form ground level ozone.

(c)

Ozone

Ozone is a naturally occurring gas in the upper atmosphere (approximately 15km to 45km above the earth’s surface). In the upper atmosphere, ozone protects the earth from harmful ultraviolet rays from the sun. However, ozone is also produced near ground level when pollutants from motor vehicles and industrial processes such as NOx and hydrocarbons react with sunlight.

At ground level, ozone is an oxidant that can irritate human nose, damage lungs and aggravate asthma. Ozone can also damage crops and other vegetation. It is a key ingredient in photochemical smog formation.

(d)

Lead

Lead is a heavy metal that was being traditionally used as an “anti-knock” agent in gasoline. Lead can also be released into the atmosphere during metallurgical processes and is used in paints and ceramic industries. Lead accumulates in the body and can retard growth, hyperactivity, impaired hearing, and even brain damage. Children are particularly sensitive to the effects of lead exposure, because of their high breathing rates.

(e)

Carbon monoxide

Carbon monoxide (CO) is a gas that is slightly lighter than air and is formed when carbon in fuel is not burned completely. In urban areas, almost all CO is produced by motor vehicles. Exposure to CO can disrupt the supply of oxygen to the body tissue, cause neurobehavioral effects and cardiovascular problems.

(f)

Sulfur dioxide

Sulfur dioxide (SO2) is a gas that is often produced in the burning of fossil fuels containing sulphur It can cause respiratory problems and damage vegetation. Sulfur dioxide dissolves easily in water and therefore can contribute to acid rain, once it released into the atmosphere.

 
The Air Quality Management Project (AQMP) has the following broad based components.
A.

Component-1: Enforcement, Standards, and Pilot Control Programs

This component, essential for the long-term success of emissions reduction measures, will include:
(i) enforcement of emissions regulations for in-use vehicles;
(ii) development of vehicle emissions standards; and
(iii) pilots for vehicular pollution control.

B.

Component-2: Air Quality Monitoring and Evaluation

This component will generate essential air quality information and evaluate pilot activities. It will include:
(i) air quality monitoring in Dhaka,
(ii) awareness raising campaigns and
(iii) air quality management assessment and strategy formulation.

 
A. i. Enforcement
 

The enforcement of emisssion standards for grossly polluting vehicles, a circucial part of regulations, is developing in Bangkadesh. When enforcement is carried out, most diesel vehicles fail emissions checks. Due to lack of manpower and poor inter-institutional co-ordination between DoE and BRTA, emisssions testing are done only infrequently. Emissions test data are not being complied systematically or analyzed. The current standards are inappropriate as they apply to all classes of vehicles, and need to be updated. DoE and BRTA also need to understand why most vehices (including new ones) fail the emissions tests. The key role of maintenance on vehicle emissions needs to be acknowledged. Programs to improve vehicle maintenance through enforcement of in-service emission standards, public awareness, mechanic training and other activities will be carried out by AQMP.

  
ii. Standards
 

There is a need to estiblish emission standards for
(a) in-use vehicle by vehicle type, to be incorporated into the inspection program, and
(b) new or used vehicles being imported into Bangladesh. The basis for a regulatory framework to control vehicular pollution will be estiblished and the level of exhaust emissions by supporting the development of appropriate standards and providing new data and experience with pilot emissions testing programs.

 
Revision of emission standards for New and Imported used Vehicles
 

DoE has revised the emission standards for new and imported used vehicles. Standards equivalent to Euro 2 for petrol and CNG vehicles and Euro 1 for diesel vehicles have been discussed and accepted by stakeholders. These standards consider current ambient air quality, fuel quality, types and numbers of vehicles being imported and trends in neighbouring countries. The draft standard has been approved by the Government.

 
Revision of emission standards for In-service Vehicles.
 

DoE has undertaken a comprehensive survey of emissions from in-service vehicles in Dhaka. The survey included measurement of idle CO and HC from approximately 1,000 petrol and CNG vehicles and free acceleration smoke from approximately 500 diesel vehicles.

The results of the survey have been used to develop a proposal for revised emission standards for in-service vehicles. The proposed standard has been discussed with stakeholders and has been approved by the Government.

 
iii. Pilots for Vehicular Pollution Control
 

Air pllutioin in Dhaka is dominated by diesel vehicular emisssions. During preparatioin activities over the past few months, technologies for diesel emissions control have been identified and proposed. While emissions from vehicles have been identified as the major cause of air pollution, the role of fuel (adulteration) and lubrication quality and maintenance of the vehicles have not been distinguished. For example, even new vehicles emit visual smoke and thus may not pass DoE or BRTA tests. This indicates that fuel quality improvement is an important issue as proper maintenance. The role of proper standards and enforcement as discussed above is crucial for controlling vehicular pollution. There is much learning and innovation needed to address the complex air pollution problem in Dhaka.

Activities under this component will include pilot testing of technical options and obtaining more information on the source of emissions and the role of fuel, lube oil and vehicle maintenance. Based on the results of the pilots, policy recommendations (including regulatory and enforcement) will be made and implemented. A few pilot studies have already been identified and others will be considered as part of the small fund for pilot study proposals.

   

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